Relays with improved organization of ratchet and contact assembly



Aug. 31, 1965 Filed June 15, 1962 J. V RELAYS WITH IMPROVED ORGANIZATION OF RATCHET FOSTER ETAL 3,204,062

AND CONTACT ASSEMBLY 2 Sheets-Sheet 1 F I G .5 INVENTORS Jo ck \I. Fostera Paul A. Hanold ATTORNEYS 1, 1965 J. v. FOSTER ETAL $204,062

RELAYS WITH IMPROVED ORGANIZATION OF RATCHET AND CONTACT ASSEMBLY Filed June 15, 1962 2 Sheets-Sheet 2 INVENTORS Jack V. Fostera Paul A.Honold FIG.7. BY mg zm, ATTORNEYS United States Patent C) 3,204,062 RELAYS WITH IMPROVED ORGANIZATION OF RA'ICHET AND CONTACT ASSEMBLY Jack V. Foster and Paul A. Hanold, Fort Branch, Ind.,

assignors to American Machine & Foundry Company,

a corporation of New Jersey Filed June 15, 1962, Ser. No. 202,852 8 Claims. (CL 200-105) This invention relates to ratchet relays generally and, while not limited thereto, finds particular application to ratchet relays wherein a plurality of contact sets are actuated as a result of movement of a simple clapper'type armature.

Though many different types of ratchet relays have been proposed heretofore, there has been a continuing need in the trade for improvement with respect to ruggedness and dependability, speed of contact actuation and simplicity of contact arrangement.

A general object of the present invention is to provide an improved ratchet relay.

Another object is to devise a ratchet relay in which a plurality of contact sets are actuated through a single pawl and ratchet mechanism as a result of movement of a simple clapper-type armature.

A further object is to provide a ratchet relay of simplified form embodying a highly advantageous contact arrangement.

Yet another object is to devise an improved ratchetoperated cam mechanism for actuating a plurality of contact sets.

In order that the manner in which these and other objects are attained in accordance with the invention can be understood in detail, reference is had to the accompanying drawings, which form a part of this specification, and wherein:

FIG. 1 is a side elevational view of a relay constructed in accordance with one embodiment of the invention;

FIG. 2 is a top plan view of the relay of FIG. 1;

FIG. 3 is a front elevational view of the relay of FIG. 1;

FIG. 4 is a rear elevational view of the relay of FIG. 1;

FIGS. 5-8 are sectional views, with some parts shown in side elevation, taken respectively on lines 55, 6-6, 77 and 8--8, FIG. 2; and

FIG. 9 is a perspective view of the pawl and ratchetoper-ated cam mechanism employed in the relay of FIG. 1 to actuate the contact sets thereof.

Turning now to the drawings in detail, it will be seen that the embodiment of the invention here illustrated comprises a generally U-shaped magnetic frame member 1, an electromagnet 2, a clapper-type armature 3, a

bracket 4 which is mounted on the frame member and carries a pair of contact spring pile-ups 5 and 6 as well as the cam shaft 7, and a pawl and ratchet mechanism indicated generally at 8.

For purposes of simplicity of description only, it will be assumed that the position of the relay seen in FIG. 1 is the normal position, so that frame member 1 can be considered as having a lower leg 9, an upright base 10, and an upper leg 11 extending in the same direction as and parallel to lower leg 9. Upper leg 11 of the frame member is shorter than the lower leg, the tip 12 thereof diverging from the main body of the upper leg to slant upwardly so as to constitute a stop for the armature. Immediately adjacent to leg 11, the upright base of 3,204,062 Patented Aug. 31, 1965 the frame member is provided with a transversely extending opening 13, as seen in FIGS. 4 and 8. As will be clear from FIG. 4, opening 13 has an upper portion which is longer, transversely of base 10, than is the lower portion of the opening, so that the end walls of the opening are provided with inwardly projecting shoulder portions 14. Adjacent lower leg 9, a tongue 15 is punched outwardly from base 10 of the frame member, as seen in FIGS. 1 and 4.

Electromagnet 2 is of the alternating current type, including an upright magnetic core secured at one end to leg 9 of the frame member and presenting a slotted pole portion 16 at its upper end. Below pole portion 16, the core is surrounded by the usual winding 17. A shading ring 18 extends through the slot of pole portion 16 and is disposed on the upper end of the bobbin for the winding, as will be clear from FIGS. 1 and 3.

Armature 3 is formed from a single sheet of magnetic material and includes a flat main body 19. At the back of the relay, a portion 20 of the armature projects from the main body 19 through opening 13 in upright portion 10 of the frame member. Armature portion 20 rests directly on the bottom wall of opening 13 and has its sides provided with aligned notches which accommodate the portions of upright base 10 which are located immediately below shoulders 14, as will be clear from FIG. 4. Portion 20 is also provided with a centrally disposed projection 21 aligned vertically above tongue 15. A helical tension spring 22 has its ends engaged respectively about tongue 15 and projection 21, as illustrated in FIG. 4, and is effective to normally pivot the armature upwardly into engagement with the stop surface provided by the slanting tip 12 of upper leg 11 of the base member. It is thus apparent that the armature is of the clapper type, resting in pivotal fashion on the lower edge of opening 13 and being normally biased upwardly by spring 22.

At the front of the relay, armature 3 is provided with a forwardly projecting flat tongue 23 which extends at a slight angle diverging downwardly relative to main body 19. As illustrated in FIG. 8, energization of electromagnet 2 pivots the armature downwardly until the lower face of body 19 engages the upwardly directed pole face afforded by pole portion 16, the pole face being disposed in the same plane as the lower edge of opening 13. When the armature is actuated to this position, tongue 23 extends slightly above the extreme forward edge of shading ring 18. v

Bracket 4, as seen in FIG. 4, has a U-shaped main portion consisting of base 24 and two upright pile-up-supporting legs 25 and 26. Spring pile-up 5 is secured to the inwardly directed face of leg 25, as by the usual mounting screws. Spring pile-up 6 is similarly secured to the inner face of leg 26.

Formed integrally with leg 25 of bracket 4 is a forwardly projecting arm 27, the arm being flat and disposed in the same plane as leg 25. Leg 26 is similarly provided with an arm 28, identical to arm 27, the two arms being disposed in opposition to each other, across 59 bracket 4 lies flush against the upper face of leg 11 of the frame member and is secured thereto by screws 30, FIGS. 2 and 8.

Cam shaft 7 is provided with a straight, outwardly opening, longitudinally extending groove 31. At a point near its center, the cam shaft carries a ratchet 32 which is fixed against rotation on the cam shaft by means of a key extending into groove 31 in the fashion shown in FIG. 8. A leaf spring 33 is fixedly mounted by the same screws 39 which secure bracket 4, the spring projecting forwardly and being of such shape that its fiat tip is maintained in engagement with the teeth of the ratchet 32. The normal operative direction of rotation for the ratchet wheel being indicated by the arrow in FIG. 8, it will be apparent that the spring 33 constitutes a stop pawl which prevents reverse rotation of the ratchet wheel.

An L-shaped mounting bracket 34 is carried by tongue 23 of the armature, the base of the L or bracket 34 being fixed to tongue 23. Fixedly projecting from one face of the upright portion of bracket 34 is a pivot pin 35. A short lever 36 is pivoted at one end on cam shaft 7, immediately adjacent to ratchet wheel 32, the pivot being such that the axis of pivotal movement of the lever is coincident with the axis of rotation of the cam shaft. Lever 36 extends radially from cam shaft 7 and is dis posed in the same plane as bracket 34. At its end opposite the cam shaft, the lever 36 is provided with a pivot pin 37 extending parallel to pivot pin 35. A link 38 has its ends pivoted to pins 35 and 37, respectively, one side face of the link lying in bearing engagement with the corresponding faces of bracket 34 and lever 36. An actuating pawl 39 is pivotally carried by pin 37 and projects into operative engagement with ratchet wheel 32, as best seen in FIG. 8. On the side of lever 36 opposite ratchet wheel 32, a torsion spring 40 embraces the cam shaft and has its ends engaged respectively under lever 36 and over the free tip of pawl 39, the effect of spring 40 being to bias the actuating pawl into engagement with the teeth of ratchet wheel 32.

. Considering FIGS. 1, 8 and 9, it will be apparent that, when electromagnet 2 is energized, the resulting downward pivotal movement of armature 3 pivots lever 36 downwardly, about the axis of cam shaft 7, and causes pawl 40 to be correspondingly moved backwardly, by one tooth, along the periphery of the ratchet wheel. The dimensions of the ratchet wheel, the actuating pawl and the operating linkage for the pawl are so selected that, when the armature reaches its lowermost position, indicated by broken lines in FIG. 8, the tip of the actuating pawl will be properly engaged with one of the teeth of the ratchet wheel in the fashion illustrated in FIG. 8. During downward movement of armature 3, backward rotation of the cam shaft is prevented by stop pawl spring 33. When the electromagnet is deenergized, biasing spring 22 causes the armature to pivot upwardly into engagement with the stop surface provided by the tip 12 of leg 11 of the frame member. Such upward pivotal movement is of course imparted to bracket 34 and therefore causes lever 36 to pivot upwardly, about the axis of the cam shaft. Such upward pivotal movement of the lever results in movement of actuating pawl 39 in a direction to rotate ratchet wheel 32, and therefore cam shaft 7, in the direction of the arrow in FIG. 8. It will thus be seen that energization of the electromagnet, and resultant downward pivotal movement of the armature, acts to store energy in spring 22 and, when the electromagnet is deenergized, the spring operates to accomplish actuation of the pawl and ratchet mechanism. This mode of operation provides more consistent operation than would be the case if the electromagnet were employed to drive the pawl and ratchet mechanism directly. Repeated cycles of energization and deenergization of the electromagnet will similarly result in a series of equal increments of rotation of cam shaft 7, all in the direciton indicated by the arrow in FIG. 8.

Spring pile-up 5 comprises a pair of spring contact arms 41 and 42 which project forwardly from bracket 4 in sideby-side relation, the two arms being provided with contacts at their tips. Contact arms 41 and 42 are electrically insulated from each other and from bracket 4 by suitable insulating blocks 43, FIG. 2, in conventional fashion. The contacts provided at the free tips of arms 41 and 42 are carried by respective adjacent side faces of the contact arms, and the arms are of such shape and disposition that, assuming that the arms are in their relaxed positions, the two contacts will engage each other. Thus, the contact set provided by arms 41 and 42 is normally closed. At aligned points immediately above the central axis of cam shaft 7, contact arms 41 and 42 are provided with bends 44 and 45, respectively, which are U-shaped in cross section and which extend transversely across the respective contact arms, as will be apparent from FIGS. 5 and 9. Bends 44 and 45 project toward each other but are still spaced apart when the contacts carried by the arms are in their normal closed position.

Mounted on cam shaft 7 at a point below contact arms 41 and 42 is an actuating cam 46 provided with a plurality of radially extending, angularly spaced fingers 47. Cam 46 is an integral body of insulating material and includes a hub 48 which is keyed to cam shaft 7 as seen in FIG. 5. Fingers 47 are of such length that, upon rotation of shaft 7, the fingers are caused to pass successively between transverse bends 44 and 45 in contact arms 41 and 42. The thickness of fingers 47, in a direction axially of the cam shaft, is greater than the normal spacing between the opposed faces of bends 44 and 45 in contact arms 41 and 42. Accordingly, when any of the fingers enters between bends 44 and 45, contact arms 41 and 42 are forced apart so that the contacts at the tips of the arms are separated. When the finger passes beyond bends 44 and 45, however, as the cam shaft is further rotated, the contact arms 41 and 42 return to their normal positions, indicated in FIG. 2, so that the contacts carried thereby are again in engagement. The angularly spaced positions of fingers 47 are accurately predetermined with reference to the amount of angular motion imparted to shaft 7 upon each actuation of the ratchet wheel by actuating pawl 39, and the cam is so positioned that one of the fingers 47 will be centered between bends 44 and 45 when the elements of the pawl and ratchet mechanism occupy the positions shown in solid lines in FIG. 8, that is, when the armature 3 is in its uppermost position. In view of this arrangement, and since there are three of the fingers 47, it will be apparent that the contacts carried by spring arms 41 and 42 are caused to open at three predetermined times during each complete rotation of the cam shaft. Further, when the pawl and ratchet mechanism is operated to cause one of the fingers 47 to become centered between bends 44 and 45, so that the contacts are opened, the contacts will then remain open until the ratchet wheel has been advanced one additional step as a result of one additional cycle of energization and deenergization of the electromagnet. This additional step of course causes the finger to be removed from between bends 44 and 45, so that the spring arms 41 and 42 return to their normal, contact-closing positions.

Spring pile-up 6, secured to leg 26 of bracket 4 across from pile-up 5, includes two sets of spring contact arms. One set consists of identical, parallel arms 49 and 50, each provided with a contact at its free tip, while the other set consists of a like pair of spring arms 51 and 52, each provided with a contact at its free tip. All of contact arms 49-52 project from the pile-up for the same distance and, in this respect, are identical with contact arms 41 and 42. As will be clear from a comparison of FIGS. 1 and 2, all of the contact arms project in normally parallel fashion and lie in a single plane. Pile-up 6 is completed by the usual insulating blocks 53, blocks 53 being effective to insulate the contacts of each pair from each other and the pairs of contacts from each other.

At a point above cam shaft 7, contact arms 49 and 50 are respectively formed with bends 54 and 55 of U- shaped cross section, the bends extending in straight lines transversely of their respective arms. Bends 54 and 55 project inwardly, that it, toward each other, but are spaced apart when contact arms 49 and 50 occupy their normal positions. Keyed to cam shaft 7 at a point centered below arms 49 and 50 is an actuating cam 56 comprising a hub 57 and a thin, flat cam disc 58 which is slotted radially, as indicated at 59. Cam 56 is made as an integral piece from insulating material. Thickness of disc 58 is such that, when a portion of the disc is located between bends 54 and 55, arms 49 and 59 are forced apart enough to separate the contacts carried at the tips of the arms. Slots 59 are of a width sufiicient to freely accommodate bends 54 and 55 so that, during rotation of the cam, the slots 59 can come into registry with bends 54 and 55 and allow arms 49 and 50 to return to their normal, contact-closing positions. Slots 59 are so angularly positioned and are of such width that unbroken portions of disc 58 will be disposed between bends 54 and 55, maintaining the contacts open, during predetermined amounts of rotational movement of the cam shaft, these amounts of rotational movement being predetermined as those which result from definite numbers of actuations of the pawl and ratchet mechanism.

Thus, assuming that one of the slots 59 is initially registered with bends 54 and 55 and that the electromagnet is then energized and deenergized sequentially, the contacts will be opened, and maintained in open position, until the next slot 59 arrives at the location of bends 54 and 55, at which time the contact arms 49 and 50 are again allowed to move toward each other until the contacts engage in their closed positions.

Contact arms 51 and 52 are provided, at points above cam shaft 7, with transversely extending bends 60 and 61. Bends 60 and 61 are of U-shaped cross section and project toward each other. Keyed to cam shaft 7' below arms 51 and 52 is an actuating cam 62, formed as an integral piece of insulating material and comprising a hub 63 and a disc 64, the latter being provided with radially extending, angularly spaced slots 65. In this particular embodiment, cam 62 is identical with cam 56 but is so positioned on cam shaft 7 that the slots 65 are angularly displaced in relation to the slots 59, as will be clear from a comparison of FIGS. 6 and 7. It will thus be apparent that, when cam shaft 7 rotates as a result of operation of the pawl and ratchet mechanism, cam 62 actuates contact arms 51 and 52 in precisely the same fashion as cam 56 actuates arms 49 and 50, except that the contact-opening and contact-closing movements resulting from rotation of cam 62 are angularly out of phase with the same movements produced by rotation of cam 56.

The configuration of the frame of the relay, the configuration and location of bracket 4 and the manner in which the spring contact pile-ups are disposed thereon, and the location and mounting for the cam shaft not only provide for a rugged but simplified structure but also allows the use of a substantial number of contact sets each employing at least two parallel spring arms, with the actuating cams disposed in lateral, wiping engagement with the spring arms, rather than in peripheral engagement therewith. While the cam members themselves are highly simplified, it will be apparent that the combination employed by the invention allows easy and accurate control of both the duration of a particular condition of the ,contacts and the relative position in time of that condition relative to the operation of other contacts of the relay. The disposition of the cam shaft, coupled with use of a lever-and-link type of motion transfer means for actuating the pawl of the pawl and ratchet mechanism makes it possible to mount all parts of the pawl and ratchet mechanism (except for the spring 33) directly on either the cam shaft or the armature, even though the armature is of the clapper type.

While one particularly advantageous embodiment of the invention has been chosen for illustration, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention, as defined in the appended claims.

What is claimed is:

1. In a ratchet relay, the combination of frame means including a first portion,

a second portion spaced from said first portion,

and

means rigidly interconnecting said first and second portions;

an electromagnet comprising a core and an energizing winding disposed about said core,

said core being fixed to said first frame portion and projecting generally toward said second portion but terminating short of the location of said second portion,

said core having a longitudinal axis and said second portion of said frame means lying in a plane transverse to said axis,

the end of said core adjacent said second portion presenting a pole face directed toward the plane occupied by said second portion;

two support members rigidly carried by said second portion of said frame means and projecting away from said electromagnet,

said support members being spaced apart in a direction transverse to said axis; an armature extending between said electromagnet and said second portion of said frame means,

said armature being mounted on said frame means for pivotal movement toward and away from said pole face about an axis extending parallel to that in which said support members are spaced apart;

a contact structure fixed to at least one of said support members;

a shaft extending parallel to said pivotal axis of said armature,

said shaft being rotatably mounted on said support members;

a ratchet wheel fixed to said shaft;

pawl means connected to said armature and arranged to rotatably advance said ratchet wheel upon each cycle of actuation of said armature toward and away from said pole face; and

means actuated by said shaft for operating said contact structure.

2. A ratchet relay in accordance with claim 1 and wherein said contact structure comprises two contact spring pile-ups each mounted on a different one of said support members, the contact springs of said pile-ups extending generally parallel to each other and generally transversely relative to the axis of pivotal movement of said armature, and

said shaft is equipped with a plurality of rotary cams fixed to and projecting radially there-from,

each of said cams being disposed to pass between a different coacting pair of said contact springs to cam the pair of contact springs apart and cause the contacts carried thereby to open as said shaft is rotated.

3. In a ratchet relay, the combination of a generally U-shaped frame structure;

an electromagnet having one of its ends secured to one leg of said frame structure,

said electromagnet extending beside the base of the U of said frame structure and terminating a short of the other leg of said frame structure to present a pole face directed toward the position of said other leg; an armature pivotally mounted on the base of the U of said frame structure and disposed between said pole face and said other leg of said frame structure,

said other leg of said frame structure presenting a limit stop; a generally U-shaped bracket,

the base of the U of said bracket being secured to said other leg of said frame structure on the side thereof opposite said pole face, the legs of the U of said bracket projecting away from said frame structure and said electromag net; a shaft extending between the legs of the U of said bracket and supported thereby for rotation about an axis transverse to the axis of said electromagnet,

the axis of rotation of said shaft and the pivotal axis of said armature being parallel; a ratchet wheel fixed to said shaft; pawl means connected to said armature and operative to rotatably advance said ratchet wheel upon each cycle of movement of said armature toward and away from said pole face; a biasing spring operatively connected to said armature to bias the same into contact with said limit stop; and switch means comprising at least one contact structure mounted on one of the legs of the U of said bracket, and contact operating means fixedly carried by said shaft. 4. A ratchet relay in accordance with claim 3 and wherein said bracket is offset from the axis of said electromagnet toward the base of the U of said frame structure, and each of the legs of said U-shaped bracket is provided with an arm portion projecting generally in the same direction as the legs of the U of said frame structure, said shaft being journaled on said arms, the axis of said shaft and the pivotal axis of said armature being located on opposite sides of the axis of said electromagnet. 5. A ratchet relay in accordance with claim 4 and wherein said switch means comprises two contact spring pile-ups each secured to a different leg of the U of said bracket, the contact springs of said pile-ups being parallel to and located between said arms, and a plurality of rotary cams fixed to said shaft and projecting radially therefrom, each of said cams being disposed to pass in lateral wiping engagement with at least one of said contact springs to actuate the same as said shaft is rotated. 6. In a ratchet relay, the combination of a generally U-shaped frame;

an electromagnet mounted on one leg of the U of said frame and presenting a pole face directed toward and spaced from the other leg of the U of said frame; an armature disposed between said other leg and said pole face and mounted for pivotal movement toward and :away from said pole face; a generally U-shaped bracket,

the base of the U of said bracket being secured to said other leg of said frame, the legs of the U of said bracket projecting away from the frame on the side of said other leg of said frame opposite said pole face, the legs of the U of said bracket being spaced apart in a direction parallel to the pivotal axis of said armature; a shaft journaled on said bracket for rotation about an axis parallel to the pivotal axis of said armature;

a ratchet wheel fixed to said shaft at a point between the legs of the U of said bracket,

the axis of said shaft and the pivotal axis of said armature being spaced from each other across the center of said pole face, said armature extending beyond the location of said shaft;

a leaf spring secured to the base of the U of said bracket and projecting into engagement with said ratchet wheel to operate as a stop pawl;

pawl means connected to said armature and operatively arranged to rotatably advance said ratchet wheel upon each cycle of movement of said armature toward and away from said pole face; and

switch means comprising a contact assembly mounted on at least one of the leg-s of the U of said bracket, and

means fixed to said shaft for operating said contact assembly.

7. In a ratchet relay, the combination of an electromagnet having a pole face; frame means on which said electromagnet is mounted, said frame means including a flat portion extending generally parallel to said pole face and spaced therefrom in the direction in which the longitudinal axis of said electromagnet extends; at least one pile-up-supporting flat member rigidly carried by said flat portion and projecting from the side thereof opposite said pole face, said pile-up-supporting member extending parallel to the axis of said electromagnet; an armature having a portion disposed between said fiat frame portion and said pole face, said armature being carried by said frame means for pivotal movement about an axis spaced laterally from and extending at right angles to the axis of said electr-omagnet, pivotal movement of said armature causing said portion of said armature to move toward and away from said pole face; switch means comprising a contact spring pile-up mounted on said at least one flat member and spaced from said flat frame portion, said pileup including a pair of parallel contact springs extending transversely of the pivotal axis of said armature; a cam shaft rotatably mounted on said at least one flat member and extending parallel to the pivotal axis of said armature, said cam shaft being disposed on the side of said flat frame portion opposite said pole face; a rotary cam mounted on said cam shaft and operatively arranged with respect to said pile-up to actuate said switch means as said cam shaft is rotated; a ratchet wheel fixed to said cam shaft; said armature having a free end portion disposed on the opposite side of said pole face from the pivotal axis of said armature; and pawl means connected to said free end portion of said armature and operatively arranged to rotatably advance said ratchet wheel upon each cycle of movement of said armature portion toward and away from said pole face, said cam shaft being located between said pawl means and the pivotal axis of said armature.

8. In a ratchet relay, the combination of a generally U-shaped frame;

an electromagnet mounted on one leg of the U of said frame and presenting a pole face directed toward from the frame on the side of said other leg of said frame opposite said pole face, i

the legs of the U of said bracket being spaced apart in a direction parallel to the pivotal axis of said armature; a pair of contact spring pile-ups each secured to a different one of the legs of the U of said bracket,

the contact springs of said pile-ups extending parallel to each other and to the planes of the legs of the U of said bracket and being spaced from said other leg of the U of said frame;

a cam shaft rotatably mounted on said bracketand extending parallel to the pivotal axis of said armature between said contact springs and said other leg of the U of said frame,

said cam shaft being equipped with a plurality of cams each including at least one radially pro- -jecting portion disposed to actuate at least one of said contact springs as said cam shaft is rotated;

a ratchet wheel fixed to said ca-m shaft at a point between the legs of the U of said bracket;

a leaf spring secured at one end to the base of the U 1 UNITED STATES PATENTS 1,183,135 5/16 Stolp 2o0 10s 1,533,188 4/25 Hargan 200-105 1,756,540 4/30 Doring et al. 200 105 10 3,106,626 10/63 Lord et a1 200-405 OTHER REFERENCES German printed application 1,035,248, July 31, 1958 5 (2 sht. dwg., 2-pp. spec.).

BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. IN A RATCHET RELAY, THE COMBINATION OF FRAME MEANS INCLUDING A FIRST PORTION, A SECOND PORTION SPACED FROM SAID FIRST PORTION, AND MEANS RIGIDLY INTERCONNECTING SAID FIRST AND SECOND PORTIONS; AN ELECTROMAGNET COMPRISING A CORE AND AN ENERGIZING WINDING DISPOSED ABOUT SAID CORE, SAID CORE BEING FIXED TO SAID FIRST FRAME PORTION AND PROJECTING GENERALLY TOWARD SAID SECOND PORTION BUT TERMINATING SHORT OF THE LOCATION OF SAID SECOND PORTION, SAID CORE HAVING A LONGITUDINAL AXIS AND SAID SECOND PORTION OF SAID FRAME MEANS LYING IN A PLANE TRANSVERSE TO SAID AXIS, THE END OF SAID CORE ADJACENT SAID SECOND PORTION PRESENTING A POLE FACE DIRECTED TOWARD THE PLANE OCCUPIED BY SAID SECOND PORTION; TWO SUPPORT MEMBERS RIGIDLY CARRIED BY SAID SECOND PORTION OF SAID FRAME MEANS AND PROJECTING AWAY FROM SAID ELECTROMAGNET, SAID SUPPORT MEMBERS BEING SPACED APART IN A DIRECTION TRANSVERSE TO SAID AXIS; AN ARMATURE EXTENDING BETWEEN SAID ELECTROMAGNET AND SAID SECOND PORTION OF SAID FRAME MEANS, SAID ARMATURE BEING MOUNTED ON SAID FRAME MEANS FOR PIVOTAL MOVEMENT TOWARD AND AWAY FROM SAID POLE FACE ABOUT AN AXIS EXTENDING PARALLEL TO THAT IN WHICH SAID SUPPORT MEMBERS ARE SPACED APART; A CONTACT STRUCTURE FIXED TO AT LEAST ONE OF SAID SUPPORT MEMBERS; A SHAFT EXTENDING PARALLEL TO SAID PIVOTAL AXIS OF SAID ARMATURE, SAID SHAFT BEING ROTATABLY MOUNTED ON SAID SUPPORT MEMBERS; A RATCHET WHEEL FIXED TO SAID SHAFT; PAWL MEANS CONNECTED TO SAID ARMATURE AND ARRANGED TO ROTATABLY ADVANCE SAID RATCHET WHEEL UPON EACH CYCLE OF ACTUATION OF SAID ARMATURE TOWARD AND AWAY FROM SAID POLE FACE; AND MEANS ACTUATED BY SAID SHAFT FOR OPERATING SAID CONTACT STRUCTURE. 